revert(ci): drop sync-pre-commit.yml

[maxpatiiuk]

.github/workflows/sync-pre-commit.yml was used to sync the .pre-commit-config.yaml between specify repositories.
This workflow is no longer maintained, and it has been failing for the past 2 years:

https://github.com/specify/specify7/actions/runs/23722008655/job/69098501569

I am deleting it since it doesn't work ever since the branch proection was enabled.
If it would be useful in the future, copilot can easily bring back a workflow like this.

Also, the workflow relied on grabbing the source pre-commit config from maxpatiiuk/dotfiles, rather than a specify-owned organzation.

This goes hand in hand with #7447

Checklist

• Self-review the PR after opening it to make sure the changes look good and
  self-explanatory (or properly documented)
• Add relevant issue to release milestone
• Add pr to documentation list - no doc needed
• Add automated tests - n/a deleting ocde
• Add a reverse migration if a migration is present in the PR
• Add migration function to

  specify7/specifyweb/specify/management/commands/run_key_migration_functions.py

  Line 50 in ea04665

  def fix_schema_config(stdout: WriteToStdOut | None = None):

Testing instructions